The present invention relates to a method and a device for reading the addresses of items of mail.
Systems for the automatic reading of addresses (OCR) are well known in the field of letter processing and are described, for example, in DE 195 31 392 C1. Using modern OCR mail sorting systems, processing rates of 10 letters per second, that is to say 36,000 letters per hour, and more can be achieved. The recognition and reliability varies sharply with the type of script and the overall quality of the address information applied to the surface of the letters, however. In the case of satisfactory recognition, the relevant item of mail can be provided with a machine-readable barcode. This barcode permits further mechanical processing up to any desired order of sorting. In particular, the use of barcodes permits sorting of the items of mail as far as the sorting level of the postal walk, in which the items of mail are sorted in accordance with the order of their distribution by the deliverer.
Since the recognition rates of the automatic reading systems vary greatly, it is necessary to assist this by means of video coding devices. Here, the video images of the items of mail rejected by the OCR device are coded manually by video coding staff at appropriate video coding stations. In the process, the addresses entered are converted into a sorting code by means of a directory.
In order to increase the coding productivity and/or to permit the indication of all the address elements, that is to say ZIP/PC, street/postbox,addressee/postbox, addressee/company, the following important methods are known:
Extraction Coding
Since, given the online delay times which can be reached in practice, only the ZIP/PC address elements can be entered reliably by the operator, specific key components are entered in extraction coding. Extraction coding is normally based on specifically developed rules, in which a code of fixed length is used as an access key to an address directory. For example, Royal Mail uses an extraction formula which is based on the first three and the last two letters. In this case, special rules have to be learned by the operator by heart, in order to avoid superfluous address information and to take account of specific discriminatory features, such as directions, for example East, West, or categories, for example Street, Lane, Road.
Selection Coding
If there are no unambiguous extracts, in which a plurality of entries in a directory correspond to the extraction code, or if the OCR unit supplies a limited number of address alternatives, then the correct address is selected by the operator in selection coding. Since, in this case, decisions have to be made instead of a simple repetitive keyboard entry, the entry productivity of the operators in selection coding is reduced as compared with extraction coding.
EP 0 975 442 B1 describes a method in which both coding methods are used in the course of the reading process. If the OCR unit is not able to read the address unambiguously during the first read attempt, extraction coding is carried out and a new OCR read attempt is carried out with the extraction result. If it is again unsuccessful and, as a result, there are still several address alternatives, the correct address is then selected during selection coding (variant 1). It is also possible for extraction coding still to have to be carried out instead and, if again no unambiguous result is achieved by this in the OCR unit, for further selection coding to have to be performed (variant 2). The disadvantage in this case is that the sequence of recognition steps is relatively rigidly defined (either variant 1 or variant 2 and in this case specifically for all items of mail). However, depending on the address of the respective item of mail, sometimes variant 1 is more efficient and sometimes variant 2. Variant 2 is always more efficient when the questionable address or the address element becomes unambiguous as a result of the entry of the extract, since extraction coding (about 2000 items of mail per hour) is faster than selection coding (about 1000 items of mail per hour). Variant 1 is more efficient in those cases when only selection coding has to be carried out instead of extraction and selection coding.